What one average trade is worth to you, after the wins and losses cancel out.
Expectancy is what an average trade puts in your pocket once the wins and losses are netted against each other. In R it shows up as EV per trade, so a system that runs at +0.2R EV gives you 0.2R on a normal trade. That one number decides whether you have a business or a hobby, literally. You can win 8 out of 10 trades and still go backwards if the 2 losers are fat enough (negative EV), which is why win rate lies to so many people.
Just split your total R / total Trades (your per trade R multiple data), and whatever is left is what a trade is worth before you take it. Above zero after costs, you have an edge. At or below zero, you are paying the market for opening trades. It says nothing about the ride, though. A system can sit at a healthy +0.3R and still put you through a 15 trade losing streak that ends your account before the average ever shows up if your risk isn't on point.
Win rate only counts how often you are right. Expectancy tells how much you make and lose too. A trend system that wins 35% of the time at +0.6R quietly beats a scalper winning 70% at +0.05R, even though the scalper feels like a genius and the trend trader feels wrong most days. The market doesn't pay you for being right. It pays you for being right about size.
It depends on how often you trade. A +0.05R edge over 2,000 trades a year is a real machine. The same +0.05R over 40 trades a year is noise you cannot tell from luck. Most retail systems that actually work land between +0.1R and +0.4R per trade after costs. If you see +0.8R... check your data before you get excited, because that is usually a tiny sample or a couple of freak trades doing the job. If you're not sure your sample's big enough, start with how many trades you need.